Variable-speed transmission



Aug. 31, 1948.

w. R. BONHAM VARIABLE SPEED TRANSMISSION Filed Aug. 51. 1946 INVENTOR.WALTER JP. BONHAM svy fwtw AT TORNEY Patented Aug. 31, 1948 UNITEDSTATES PATENT OFFICE 2,448,249 VARIABLE-SPEED TRANSMISSION WalterRichard Bonham, Palo Alto, Calif. Application August 31, 1946, SerialNo. 694,376 3 Claims. (Cl. 74-1895) 1 This invention relates toautomatic variable speed transmissions of the type adapted for use withautomotive vehicles.

An object of my invention is to provide a novel variable ratio drivemechanism employing a fluid coupling and a planetary gear system.

Another object or my invention is to provide an automatic variable ratiodrive mechanism for transmitting power from a drive shaft to a drivenshaft, embodying a fluid coupling having its impeller rigidly connectedto the drive shaft and its runner connected to the driven shaft througha planetary gear system which is capable of being selectively controlledto effect the rotation of the driven shaft either in the same directionthe drive shaft is rotating or in a reverse direction.

Another object ofmy invention is to provide a variable speedtransmission of the kind which will automatically and progressivelyadjust itself to the driving conditions and the engine load without theuse of manually operable gear shifting or clutch means.

Other and further objects of my invention will be pointed outhereinafter, or will be indicated in the appended claims, or will-beobvious to one skilled in the art upon an understanding of the presentdisclosure. For the purpose of this application I have elected to showherein certain forms and details of a variable speed transmissionrepresentative of my invention; it is to be understood, however, thatthe embodiment of my invention herein shown and described is for thepurpose of illustration only andthat therefore it is not to be regardedas exhaustive of the variations of the invention.

In the accompanying drawings:

Figure l is a vertical longitudinal sectional view'of a variable speedtransmission embodying the principles of my invention;

Figure 2 is a sectional view of a fragmentary part of the control meansassociated with the transmission; and

Figure 3 is another sectional view of the control means, takensubstantially along the line 3-3 of Figure 1.

The fluid coupling selected for illustration purposes is well known inthe art to which the present invention relates and requires no detaileddescription, it being sufiicient for purposes of this specification tostate that it comprises a vaned impeller I positioned in opposedrelation to a vaned runner 2. The impeller l is suitably secured as at 3to the driving shaft 4 of an engine and is rotated thereby. The runner 2is bolted to an outwardly extending annular flange 5 another but smallergear I! formed at one end of a sleeve 6 which is rotatably mounted onthe driving shaft 4. The sleeve 6 is formed at its opposite end with acarrier 1 having a plurality of uniformly spaced spindles 8 securedthereto. I

Rotatably mounted on each of the spindles 8 is a tubular shaft 9 havinga planet gear l0 fixed to one end thereof and another smaller gear llkeyed to its opposite end. The driving shaft 4 carries a sun gear l2which operatively engages with the planet gears Ill.

The driven shaft i3 is piloted as'at II in the inner right hand end ofthe driving shaft 4, and

secured rigidly to the former's inner or left hand end is a sun gear l5which cooperates with a plurality of planet gears l6 rotatably mountedon the tubular shafts 9. The driven shaft l3 carries which cooperativelyengages with a plurality of planet pinions each of said planet pinionsbeing rotatably mounted on individual shafts l9 supported on the hubportion of a disc-like carrier 20.

Cooperating with and interposed between the pinions l8 and the smallgears l l is a ring gear 2| having internal and external teeth, the saidring gear being carried by the hub portion of a connecting web 22. Theconnecting web 22 is rotatably mounted on the hub portion of the carrier20. Carried at the periphery of the web 22 is an 1 internal ring gear 23which constitutes an orbit for a planetary gear train. Rotatably mountedon shafts 24 secured to a ring-shaped carrier 25 are planet gears 26which operativelyengage with a ring gear 2'! having teeth providedinternally and externally thereon. The ring gear 21 operatively engagesinternally with the gears i5 rotatably mounted on the tubular shafts 9.

Cooperating with the disc-like carrier 20 and the ring-shaped carrier25, respectively, are brake bands 28 and 29, which when tightened willhold their respective carriers against rotation. Suitable means,operable preferably from the driver's seat of the vehicle, is providedfor selectively faces 3! arranged thereon,

bringing either of the brake bands into operative relationship with itsassociated carrier. Since either one or the other of the carriers 20 or25 is held stationary while the other is rotating, depending uponwhetherto bring one of the brake bands into operative engagement with itsassociated carrier while the other is disengaged from its associatedcarrier. A shiftable bar 30 having oppositely inclined suris mounted onthe housing 32 in cooperative relationshi with the forward or reversemotion Y is to be imparted to the vehicle, it is necessary brake bands28 and 29. A lever 33, pivoted at 94 and connected to one end of theshiftable bar 90, when moved to the left (Figure 3) will contactdirectly transmitted by the driving shaft 4 to the gear l2 which isthereby rotated to cause the planet gears l and the small gears H torotate. Until either of the carriers 20 and 25 are held stationary, thedriven shaft I3 is free of driving due to the fact that the slip in thefluid coupling is substantially one hundred percent and practically nodriving force is being transmitted from the impeller to the runner. Withan increase in the engine torque the runner 2 discontinues its reverserotation and begins to rotate with the impeller, thereupon transmittingdrive to the By applying the brake band 29 and preventing the rotationof the ring-shaped carrier 25 driving torque in the direction of thedriving shaft 4 is transmitted to the driven shaft through the carrier1, the tubular shafts 9, the small gears H, the ring gear 2|, the web22, the ring gear 23, the planet gears 26, the ring gear 21, the planetgears l6 and the sun gear l5. It will be noted that such rotation of thecarrier I automatically and progressively decreases the reduction gearratio until the fluid coupling is operating with its minimum slip andthe total reduction ratio is a minimum.

Reverse is obtaned by shifting the bar 30 to a continued and the saidcarrier freely rotates about the said ring gear 21 without impartingrotary motion thereto. With the carrier 29 secured against rotation thereverse drive of the driven shaft I3 is effectuated from the carrier 1,through the tubular shafts 9, the small gears H, the ring gear 2|, theplanet pinions l8 and the ear l1.

The transmission automatically adjusts itself to the engine load, andsince gear shifting is entirely eliminated its operation is silent andsmooth.

What I claim is:

1. An automatic variable-ratio drive mechanism comprising driving anddriven shafts, a fluid coupling including an impeller and runner, saidimpeller secured to the driving shaft, a carrier mounted for rotationabout the driving shaft and connected in driving relationship with therunner rotating the driven shaft in the opposite direction, and controlmeans for selectively operatively connecting either of the gear trainswith the driven shaft.

3. An automatic variable-ratio drive mechanism comprising driving anddriven shafts, a fluid coupling including an impeller and a runner, saidimpeller secured to the driving shaft, rotatable means connected both tothe runner of the fluid coupling and to the driving shaft, 9.sun-andplanet and ring gear combination connecting the rotatable meansand the driven shaft for forward driving. a second sun-and-planet andring gear combination connecting the rotatable means for reversedriving, and control means for selectively bringing either of the saidgear combinations into or out of operative driving relationship with thedriven shaft.

WALTER RICHARD BONHAM.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Hanson Feb. 25, 1947

